Celldex breast cancer drug shrinks some tumors-study

(Reuters) - Interim results from a mid-stage trial of Celldex Therapeutics Inc's experimental drug showed trends toward reducing tumors in patients with advanced breast cancer, with rates improving for those patients with high levels of a key protein.

The drug, CDX-011, which links a tumor-targeting antibody to a cell-killing chemotherapy drug, was tested in 122 patients whose breast cancer had progressed despite several previous rounds of standard therapy.

In the study, released by the company on Wednesday, 19 percent of patients taking CDX-011 saw their tumors shrink, compared with 14 percent of those treated with standard chemotherapy.

CDX-011 is designed to target GPNMB, a protein produced on the surface of several types of malignant tumors. In trial patients with GPNMB on at least 25 percent of tumor cells, 32 percent responded to the drug, compared with 13 percent of chemotherapy patients.

"GPNMB helps the tumor cell to move around," said Dr. Linda Vahdat, director of the breast cancer research program at Weill Cornell Medical College and the study's lead investigator. "It almost seems like this drug puts the brakes on that process by taking away its legs."

For patients with high levels of GPNMB as well as "triple negative" breast cancer -- meaning cancer that is not sensitive to estrogen, progesterone or a protein known as Her2 -- the response rate was 36 percent compared with no responses in the control group.

Side effects associated with CDX-011, also known as glembatumumab vedotin, included rash and peripheral neuropathy.

The company said it expects to announce updated results from the Phase II trial in the fourth quarter of this year.

"This patient population has a very real need," said Tom Davis, chief medical officer at Celldex. "It is reasonable to consider a single-arm study ... a randomized study is also a possibility."

About 15 percent of breast cancer patients are triple negative, while high expression of GPNMB occurs in about 27 percent, according to Celldex. Because there is some overlap, both groups account for an estimated 35 percent of the total breast cancer population.

About 227,000 U.S. women are diagnosed with invasive breast cancer each year, according to the American Cancer Society.

Chief Executive Officer Anthony Marucci said Celldex will consider partnerships to develop CDX-011, but plans to move forward with the drug regardless of any such deals.